The invention relates to a device for indexed adjustment of the position of the moving part that is suitable for being displaced in rotation about an axis relative to a support part, the support part being fixed relative to the axis.
In an embodiment of the invention, the moving part is the armrest of a seat, e.g. for a motor vehicle.
In conventional manner, such armrests are:
adjustable in angular position in a vertical plane relative to a reference plane that is generally horizontal; and
retractable into a position that is conventionally located in the plane of the seat back.
Very many embodiments of devices for adjusting the position of a motor vehicle seat armrest are already known in the prior art.
By way of example, reference can be made to the following documents: DE-A-43 30 448, DE-A-42 27 871, DE-40 22 840, DE-36 11 929, EP-A-010 867, EP-A-018 662, EP-A-061 967, EP-A-104 040, U.S. Pat. No. 4,807,935, FR-A-2 406 752, FR-A-2 636 278, and FR-A-2 704 661.
Reference is made below more particularly to document FR-A-2 737 263 which stems from the Applicant.
In a first embodiment, shown in FIGS. 2 to 9 of that document FR-A-2 737 263, that prior device makes it possible, starting from a first extreme position P1 of the moving part and moving it in a first direction of rotation S1:
initially to move the moving part stepwise until it reaches an intermediate position P3; and then
secondly, beyond the intermediate position P3, to move the moving part freely, in the direction of rotation S1 and also in the opposite direction S2, such that the moving part is capable:
either of being returned to its first extreme position P1 by rotating freely in the direction S2, resilient means then optionally urging the moving part in the direction S2;
or else of being taken to a second extreme position P2 by rotating freely in the direction S1, resilient means then optionally urging the moving part in the direction S2.
The incremental or step-by-step movement is provided by a ratchet mechanism having a rocking pawl with teeth, suitable for taking up the following states which are defined relative to the pawl and a ratchet disposed on a part secured to the moving part:
a state in which the teeth of the pawl are spaced apart from those of the ratchet, the moving part then being capable of being displaced freely in rotation in both directions S1 and S2;
a plurality of full thrust states in which the teeth of the pawl bear against the teeth of the ratchet, each state corresponding to a given position of the moving part which can then be displaced in the direction S1 only; and
a plurality of adjustment states, in each of which only one of the teeth of the pawl is in contact with the ratchet, there being an adjustment state between each of the full thrust states during rotation of the moving part in the direction S1 between the positions P1 and P3.
A resilient member continuously urges the pawl towards the ratchet.
The part supporting the ratchet is provided with a cam path for actuating means for declutching rocking of the pawl.
The cam path has abutments which, when they bear against opposing abutments provided on the pawl, enable:
the pawl to pass from a full thrust position to the spaced-apart position during rotation of the moving part in the direction S1; and
the pawl to return from its spaced-apart position to a first full thrust position by rotating the moving part in the direction S1 and returning to the first extreme position P1.
Resilient means ensure that the pawl is held in the spaced-apart position so long as the cam path has not caused the pawl to return to the full thrust position, which is obtained by rotating the moving part in the direction S2 all the way to the first extreme position P1.
In the device described by document FR-A-2 737 263, numerous housings are formed in the fixed part for receiving resilient means that act on the rocking pawl, thereby complicating implementation of such a fixed part and making a compact embodiment difficult to achieve.
In addition, the device described in document FR-A-2 737 263 has numerous parts to assemble whose dimensions, configuration, and materials give rise to high manufacturing costs.
The invention relates to a device enabling the same functions to be performed as are obtained from the first embodiment described in document FR-A-2 737 263, while being more compact and more robust, and while also making it possible:
to be removed from the armrest without tools, with no projecting portion overhanging the seat when the armrest is removed from the device;
to have an assembly with a smaller number of parts compared with prior embodiments; and
to be mounted on a symmetrical armrest on a device situated on the right or the left of a seat without requiring significant modification to the device.
To this end, in a first aspect, the invention provides a device for automatic indexed guidance of a moving part guided about an axis of rotation on a fixed part that is fixed about said axis of rotation, the device comprising:
a toothed element mounted to rock about a rocking axis substantially parallel to the axis of rotation;
a ratchet defining a plurality of abutments for the toothed element, said abutments being angularly disposed around the axis of rotation; and
a cam path for controlling the rocking movements of the toothed element about its rocking axis during rotation of the moving part;
said device comprising a first rigid one-piece fixed cheek-plate provided with a plurality of staged surfaces defining:
the ratchet;
the cam path; and
at least one bearing surface suitable for guiding
a moving plate in rotation about the axis of rotation, the moving plate supporting the rocking axis of the toothed element.